Friday, March 22, 2019

An excuse to repost one of the few times probability, classic TV and horse racing collide




It is with profoundly mixed emotions (though surprise is not among) that I have to admit that Matt Novak got here first in his indispensable Paleo-Future.











Thursday, March 21, 2019

Some stories I'm keeping an eye on

















Wednesday, March 20, 2019

SpaceX is betting on technological stagnation

This isn't exactly a new thought, but I don't think I've ever consciously framed it in just these words before. As we've observed before, SpaceX is making real and important advances, but it is incremental  progress built on technology that is, at its core, over a half century old.

Not only was SpaceX never really the disruptor it was billed as; its position depends on no real disruptor entering the industry. Now it may be facing two, and if both should come through, it is not entirely clear how much of a niche would be left between them.

It is difficult to know for certain how much progress those Russian engineers are making on nuclear rockets, work on a workable spaceplane seems to be moving along at a nice pace.


Not only would Sabre power units enable rapid, point-to-point transport inside the atmosphere, but they would also allow reusable vehicles to make the jump straight to orbit without the need for multiple propellant stages - as is the case now with conventional rockets.

Sabre would work like an air-breathing jet engine from standstill to about Mach 5.5 (5.5 times the speed of sound) and then transition to a rocket mode at high altitude, going at 25 times the speed of sound to get into space, if this is the chosen destination.
...

The essential innovations include a compact pre-cooler heat-exchanger that can take an incoming airstream in the region of 1,000C and cool it to -150C in less than 1/100th of a second.

REL proved the pre-cooler's efficiency at taking an ambient air stream to low temperature in 2012. Now it must do the same in a very high-temperature regime. This is the purpose of the Colorado tests.

"To have a very high-temperature, high-volume flow of air to test the pre-cooler - we needed a new facility. That is now complete," explains Shaun Driscoll, REL's programmes director

"We will be running tests in the next month or two. We will be using re-heated aero engines to drive air through the system. We will drive air into the pre-cooler at up to 1,000C."
...

REL is a private venture with the backing of aerospace giants BAE Systems, Rolls-Royce and Boeing. It has also received significant R&D support from the UK government. Esa's propulsion specialists act as technical auditors, assessing each step in the development of the Sabre concept.



Tuesday, March 19, 2019

"Significant negative indicator" is a beautiful piece of understatement

Threads like this by Jawad Mian are one of the best reasons to stick with Twitter.


5) VCs raising ever-larger funds at an increasing pace, despite a lack of viable opportunities. Sequoia raised $8bn, largest ever by US venture firm. “It’s easier to raise money than anytime I’ve been in the business," said David Rubenstein. Does not bode well for future returns.
6) Gulf money is notoriously late to the party, purchasing Carlye Group in 2007 at the peak of the credit bubble, and anchor investors in Glencore IPO in 2011 at the peak of the commodity bubble. Now they are "all in" on Uber and opened offices in Silicon Valley to do more.

7) Discipline is loosening considerably. @bfeld noted, "A number of companies, often times with nothing more than a team and a Powerpoint presentation, have had great success raising capital north of that $10 million level... I view this as a significant negative indicator."
...

10) After the new SEC chairman, Jay Clayton, “pledged” to look after ordinary investors upon taking the job, he said he wants to make it easier for small mom-and-pop investors to invest in private companies.
...

14) Uber's new CEO said, "We suffer from having too much opportunity right now as a company." Uber addresses this ailment by burning money some $20 billion since it’s founding a decade ago and now accessing public markets as private capital is tapped out.

15) A century ago, railroad entrepreneurs found a ready market to fund their massive expansion plans based on an extreme overestimation of the market opportunity. This ended badly, of course, and holds more parallels to today’s ride-sharing companies than we might like.
16) On seeing the announcement of a new issue of stock by the Northern Pacific and Great Northern roads, Jesse Livermore said, “The time to sell is right now... If money already was that scarce and the railroads needed it desperately. What was the answer? Sell ’em! Of course!"

Lots more good stuff. Give it a read.


Monday, March 18, 2019

Possibly the biggest mistake the left ever made was demonizing nuclear over coal.

I've said this before and I'm always surprised how little pushback I get.

Hans Blix writing for Time:

Can we responsibly continue to rely on nuclear power after the big accidents at Three Mile Island, Chernobyl, and Fukushima? Those were three grave accidents, yes, but accidents in any industry, whether nuclear, aviation or others, lead also to new, safer designs and dedication to safety culture. Plane crashes have not stopped us from flying, because most people know it is an effective means of traveling. They know that risks are rarely zero but also that safety is very high. We must arrive at a similar acceptance of nuclear power.

There was a time, in the early atomic age, when nuclear-generated electricity was expected to be “too cheap to meter” — that it would be more effective, in other words, to provide it for free than to charge. In the end, it did not exactly turn out that way. Nuclear power has never been cheap and today it struggles to be competitive on purely economic grounds with electricity generated by burning natural gas — especially from fracking in the United States. However, the story is very different if we see emissions of greenhouse gases as a cost in themselves. According to a 2011 study, taken on average over the lifetime of an energy plant, the burning of coal results in 979 tons of carbon-dioxide (per gigawatt hour) entering the atmosphere. Gas gives off 550 tons. The figure for nuclear power is just 32 tons.

Some people claim we can manage the world’s great and increasing hunger for energy by using wind and solar power. The call for “renewable energy sources” excludes fossil fuels, but it also excludes nuclear power, which is based on non-renewable uranium resources. It has been a smart but facile message, and we should be grateful that the world’s two most populous countries — China and India — are fast expanding their use of nuclear power as well as of renewables. Solar and wind power are great in many places and have gone down in cost. However, getting rid of technically sound carbon dioxide-free nuclear power plants, to replace them with carbon dioxide-free wind and solar plants, does not make environmental sense. And to reject nuclear power because uranium is not renewable is silly. With modern technology the global resources of uranium and thorium could fuel thousands of years of expanded use of nuclear power. Is it not enough that they are sustainable?

Friday, March 15, 2019

Fascinating little Oscar-winning glimpse into postwar (1949) attitudes toward public health care directed by the great Chuck Jones.



Thursday, March 14, 2019

The appeal of elite schools -- old thoughts on a new controversy

From September 29, 2010

The heroin's still doing the heavy lifting -- why Ivy League legacies work

From Christopher Shea's Boston Globe column:
Richard D. Kahlenberg, editor of the forthcoming book "Affirmative Action for the Rich: Legacy Preferences in College Admissions," points out that universities in other countries don't give so-called legacy preferences to sons and daughters of their alumni. (Even Oxbridge colleges don't, despite the class-bound history of British education.) So, he asks, why on earth do we do it in America?
Broadly speaking, students go to college in search of four things: certification; instruction; reputation; and connections.

In terms of certification, any well-accredited school would do. In terms of undergraduate instruction, the best deal for the money (and perhaps the best deal period) is the small four-year school. (I'm leaving this as an assertion but I'm fairly confident I can argue the point if anyone wants to debate.)

In the next two categories, however, the Ivy League cannot be surpassed, in part because of the legacy system.

Without loss of generality, look at Harvard. The student population of the school consists entirely of two overlapping groups: people who can get into Harvard; people whose parents can get them into Harvard.

The first group is hard-working, ambitious and academically gifted. Assuming the number of need-based legacies is trivial, the second group comes from families that are wealthy (they're paying for a Harvard education) and well-connected (at least one parent went to Harvard).

Putting aside luck, you can put the drivers of success into three general categories: attitude, drive and work habits; talent, intelligence and creativity; reputation and connections. It is possible to succeed with just one of these (hell, I can think of people who made it with none), but there is a strong synergistic effect. A moderate talent who works hard and has connections will generally go farther than a spectacular talent who's lazy and isolated.

Connections are governed by the laws of graph theory. I'm not going to delve too deeply into the subject (since that would require research and possibly actual work on my part), but as anyone who has read even the cover blurbs on Linked or Small Worlds can tell you, adding a few highly connected nodes (let's call them senator's sons) can greatly increase the connectivity of a system.

It would be interesting to model the trade off between picking a well connected legacy over a smarter, harder-working applicant given the objective of producing the greatest aggregate success. Because of the network properties mentioned above, it wouldn't be surprising if the optimal number of legacies turned out to be the 10% to 15% we generally see.

Optimized or not, this mixture is almost guaranteed to churn out fantastically successful graduates regardless of what the schools do after the students are admitted. I'm certain the quality of instruction on the Ivy League schools is very good, but, like most education success stories, the secret here is mostly selection and peer effects.

Update: For a different interpretation (this time with actual data), check out this post at Gene Expression.

Updated update: Why doesn't spell check work in the title field?

Wednesday, March 13, 2019

Guess which side I'm on...



Here's a hint:

Wednesday, April 3, 2013

More on journalistic tribalism

Having brought up the charge in a previous post, I should probably take a minute to spell out exactly what I'm talking about. I'm using a very broad reading of the term 'tribalism' (perhaps so broad I should say something like 'tribalism and other social psych phenomena'). The traits I'm thinking of include:

1. Us/them mentality;

2. Excessive reliance on in-group social norms;

3. Deferring to and preserving hierarchies;

and as a consequence

4,   A tendency to use different standards to judge interactions based on the relative positions of the parties.

There is inevitably going to be a degree of subjectivity when deciding who goes where in the hierarchy, but I think it's fairly safe to say that Maureen Dowd and (till his death) Michael Kelly were in the innermost circle with writers like David Brooks and most prominent, established Washington and, to a lesser degree, New York journalists fairly close.

In this tribal model, it makes perfect sense that Politico would view Chris Hughes' (outsider) request for a small change in the copy of Timothy Noah (insider) as a major affront. It also explains Politico's attacks on Nate Silver (outsider) when his work started making established pundits (insiders) look bad.

The press corps's treatment of Al Gore in 2000 is another case in point. Following the lead of Dowd and Kelly and reinforced by a general dislike of the candidate, the group quickly established social norms that justified violating the most basic standards of accuracy and fairness.

The poster child for this kind of journalistic tribalism is Jack Shafer, or at least he was a few years ago when I was first experimenting with blogging. One of my main topics was the press's inability to face up to its problems and Shafer was the gift that kept on giving (I haven't read him much since). That blog is gone now but I still have my notes so here are some highlights.

Shafer was openly disdainful of readers and generally dismissive of their interests which is an extraordinary starting point for a journalism critic. Consider this passage from the aptly named "Why I Don't Trust Readers"
I'm all for higher standards, but I draw the line when journalists start getting more complaints about less serious professional lapses. Serious: Plagiarism, willful distortion, pattern of significant errors, bribe-taking. Not serious: campaign donations in the low three-figures for reporters distant from that beat; appearance of conflict of interest; a point of view; friendships with the rich and powerful.
First, notice the first item on the list. Plagiarism is certainly a serious offense, but the other serious offenses are the sort of things that can destroy people's lives, conceal crimes and enable corruption. Even more interesting is what didn't make the list: unintentional distortion due to laziness or bias; patterns of minor errors; isolated cases of serious errors due to negligence; selective reporting (as long as it doesn't rise to the level of distortion); failure to dig into important aspects of a story; cozy relationships with subjects as long as it doesn't involve the quid pro quo of a bribe.

What's important here was the victimology. In plagiarism, the primary victim is a fellow journalist. In all of these other cases, the primary victim is either the subject or the reader. Shafer was a tribalist and his main objective was almost always the defense of his tribe and its hierarchy.

There's a remarkable inverse correlation between the rank of Shafer's subjects and the harshness with which he treats them.  This is particularly apparent when different subjects of the same article have different positions. Shafer provided an excellent example when he wrote a post complaining about liberals writing books that actually called conservatives liars in the titles.

The books were Al Franken, Lies and the Lying Liars Who Tell Them,  Joe Conason's Big Lies and David Corn's The Lies of George W. Bush. Of these three, Conason was something of a pariah (Shafer dismissed him as a Clinton apologist) and Franken was clearly a journalistic outsider. Corn, on the other hand, was very much an insider in the Washington press corp (Shafer even described him as a friend in the post).

Under these circumstances, it's not surprising that Shafer finds a way to shield Corn from much of the blast.
This criticism applies more to Franken and Conason than it does Corn—you can't expect a book about Bush's lies to also be about Clinton's lies. And Corn acknowledges in his intro that Bush isn't the first White House liar and that Clinton lied, too. 
Of course, you could easily make a similar but more persuasive argument in Franken's behalf. Lies was largely focused on the relationship between the GOP and conservative media and since the book was published in 2003 when there was no Air America and MSNBC was just starting to experiment with liberal programming, there was no way to provide similar examples on the left.  Just to be clear, I'm not making that argument; I'm only saying that it's just as viable as the one makes for Corn.

For an even more dramatic bit of paired data, consider two obituaries Shafer wrote, separated by only a few months. The first was for Walter Annenberg, best known as a philanthropist and founder of TV Guide. The second was for Michael Kelly, journalist and former editor of the New Republic. Once again there's a clear hierarchical distance between the subjects: Annenberg, though decades earlier a power in publishing and to his death a major force in philanthropy, was not a journalistic insider; Kelly, on the other hand was about as inside as you can get.

As you've probably guessed by now, Shafer's approach to these two obituaries differs sharply. Though they don't fully capture the difference, the epitaphs give a good indication of the respective tones:

Michael Kelly: "Husband. Father. Journalist"

Walter Annenberg: "Billionaire Son of Mobster, Enemy of Journalism, and Nixon Toady Exits for Hell—Forced To Leave Picassos and van Goghs at Metropolitan Museum."

The contrast is sharpest when Shafer addresses journalistic scandals and cozy relationships with controversial right wing politicians, areas where there are definite parallels between the two men. Shafer actually explains away the New Republic/Glass scandal as an instance of Kelly being too loyal for his own good.

Shafer often judges figures on the periphery of the journalistic establishment based on a much higher standard than "Plagiarism, willful distortion, pattern of significant errors, bribe-taking." For someone like Larry King, a few disputable errors and minor discrepancies (such as changing the date of an incident from 1972 to 1971 when retelling an anecdote) merit an entire column. (It's worth noting that this column ran in the middle of 2009, a period when the coverage of politics, the economy and the European crisis were raising all sorts of journalistic questions, questions that didn't get a lot of space in Shafer's column. This raises the issue of trivialism in media criticism -- see On the Media for a myriad of examples -- but that's a topic for another thread.)

If marginal figures committing minor offenses are treated harshly by Shafer, what happens when someone at the top of the hierarchy does something that Shafer normally considers a serious offense like plagiarism? We got an answer to that one when Maureen Dowd was caught lifting a passage from Josh Marshall.

Here's her explanation in Bloggasm:

“i was talking to a friend of mine Friday about what I was writing who suggested I make this point, expressing it in a cogent — and I assumed spontaneous — way and I wanted to weave the idea into my column. but, clearly, my friend must have read josh marshall without mentioning that to me. we’re fixing it on the web, to give josh credit, and will include a note, as well as a formal correction tomorrow.”
And here Shafer explains why it's not so bad:
1. She responded promptly to the charge of plagiarism when confronted by the Huffington Post and Politico. (Many plagiarists go into hiding or deny getting material from other sources.)

2. She and her paper quickly amended her column and published a correction (although the correction is a little soft for my taste).

3. Her explanation of how the plagiarism happened seems plausible—if a tad incomplete.

4. She's not yet used the explanation as an excuse, nor has she said it's "time to move on."

5. She's not yet protested that her lifting wasn't plagiarism.

6. She's taking her lumps and not whining about it.
And here was my response at the time:
1. 'Responded.' Not to be confused with 'confessed,' 'owned up,' 'took responsibility,' or any phrase that uses a form of the word 'plagiarism.'
2. "[A] little soft"?
3. Yeah, near verbatim quotes make it through convoluted processes all the time.
4. "[M]y friend must have read josh marshall without mentioning that to me." -- What exactly would an excuse look like?
5. No, she just implied it wasn't plagiarism. That definitely gives her the moral high ground.
6. What a trooper.
(I apologize for the tone. I was in a snarky phase, but I'm trying to play nicer these days.)

I've spent a lot of time on Shafer because he's a good example,  I was familiar with his work and, as a media critic, he has an important role in journalism's self-correction process, but he's is not an isolated case, nor is he the worst of bunch (particularly not since the rise of Politico).

The point of all this is that journalism has a problem with tribalism and other social dynamics. These things are affecting objectivity, credibility and quality. What's worse, journalists seem to have so internalized the underlying mindset to such a degree that most of them don't even realize what's going on.










Tuesday, March 12, 2019

I don't say enough nice things about Ars Technica -- AV Edition

This recent piece is a must read for anyone following this story byTimothy B. Lee

Tesla is clinging to an old conventional wisdom

In 2014, the same year Tesla started shipping the first generation of Autopilot hardware, the Society of Automotive Engineers published a five-level taxonomy of autonomous driving systems that envisioned driver-assistance systems (known as "level 2" in SAE jargon) gradually morphing into fully autonomous systems that could operate without human supervision (levels 4 and 5).
But the last five years have seen a dramatic shift in industry thinking. Most companies now see driver assistance and full self-driving as distinct markets.

No company has done more to change industry thinking here than Google, whose self-driving project was spun off as Waymo in 2016. Around 2012, Google engineers developed a highway driving system and let some rank-and-file Googlers test it out. Drivers were warned that the system was not yet fully autonomous, and they were instructed to keep their eyes on the road at all times.
But the self-driving team found that users started to trust the system way too quickly. In-car cameras showed users "napping, putting on makeup and fiddling with their phones." And that created a big safety risk.

"It's hard to take over, because they have lost contextual awareness," Waymo CEO John Krafcik said in 2017.

So Google scrapped plans for a highway driver assistance product and decided to pursue a different kind of gradualism: a taxi service that would initially be limited to the Phoenix metropolitan area. Phoenix has wide, well-marked streets, and snow and ice are rare. So bringing a self-driving service to Phoenix should be significantly easier than developing a car with self-driving capabilities that work in every part of the country and all weather conditions.

This approach has some other advantages, too. Self-driving cars benefit from high-resolution maps. Gathering map data in a single metro area is easier than trying to map the whole world all at once.
Self-driving cars also benefit from lidar sensors, and the best ones cost thousands—if not tens of thousands—of dollars each. That's too expensive for an upgrade to a customer-owned vehicle. But the economics are more viable for a driverless taxi service, since the self-driving system replaces an expensive human taxi driver.

Over the last three years, most other companies working on self-driving technology have followed Waymo's lead. GM bought a startup called Cruise in 2016 and put it to work developing an autonomous taxi service in San Francisco. Ford made a similar bet on Argo AI in 2017—the company is now developing autonomous taxi services in Miami and Washington DC.
Volkswagen and Hyundai have deals with Aurora—a startup co-founded by Chris Urmson, the former leader of the Google self-driving project—to develop fully autonomous taxi services. Technology companies like Uber and Zoox are planning to introduce autonomous taxi services.

Tesla’s business model locks it into the old approach

Tesla, meanwhile, has stubbornly pushed forward with its original strategy. For more than two years, Tesla charged customers $3,000 or more for a "full self-driving" package. But progress has been slow. And that has put Tesla in a bind. Abandoning the old strategy would likely require refunding customers who paid for the Full Self-Driving package—which would be both embarrassing and expensive.

Instead, Tesla's solution has been to move the "full self-driving" goal posts.

"We already have full self-driving capability on highways," Musk said during a January earnings call. "So from highway on-ramp to highway exit, including passing cars and going from one highway interchange to another, full self-driving capability is there."
Obviously, this statement comes with a big asterisk: the driver still has to supervise the car to make sure it doesn't crash.

Monday, March 11, 2019

Friday, March 8, 2019

We won't even get into the intellectual property theft angle and the original Captain Marvel

It's late and this hits a lot of threads, so I'm just going to hit the high points.

Lots of fans feel a sense of ownership over the characters and franchises they follow.








The intersection between fandom and the alt-right has grown increasingly, if you'll pardon the word, fanatical. Perhaps the ugliest corner is dominated by the men's rights movement.

From the Hollywood Reporter:
Such messages are, of course, not actually reviews of Captain Marvel the movie — that there’s no way any of these people have actually seen a film that hasn’t been released yet is a clue, perhaps — but instead the very fact that Marvel is finally releasing a movie with a woman at the forefront, and that the actor playing the role has been outspoken about real-world issues surrounding sexism, racism and ableism. In other words, it’s more of the same kind of attempts to derail progressive Marvel movies that saw faked accounts of assault by African-Americans at Black Panther screenings last year.

That shouldn’t come as much of a surprise, considering the kind of sexist and racist trolling that surrounded 2017’s Star Wars: The Last Jedi, and particularly Kelly Marie Tran’s character Rose Tico; genre properties, especially tentpole projects and those released by massive studios like Disney or Warner Bros., have had to contend with increasingly vocal swathes of bigotry online in recent years as power structures inside the movies shift away from white male heroes.

Perhaps the best commentator on the alt-right wing of fandom and andd one of the best on the business of pop culture is Bob Chipman. Here, he points out that Disney does have a hidden agenda and it has nothing to do with social justice, and everything to do with lax enforcement of anti-trust laws.





Thursday, March 7, 2019

What used to be called the Show Me State

Via the comment section, Virgin Hyperloop One is finding a receptive audience for its pitch. [emphasis added]

With the feasibility of a high-speed Missouri Hyperloop route connecting Kansas City to St. Louis in about 30 minutes now established, the conversation has shifted tracks to ergonomics, said Diana Zhou.
Perhaps even more than Mars One, the hyperloop narrative illustrates the power of ignoring irrefutable criticism. Since long before Elon Musk coined the term (still his only real intellectual contribution to the project), the obstacle that has prevented maglev vactrains from catching on has been the enormous costs of major construction with tolerances that tight, followed by the still unsolved problem of high speed stability.

Other than some hand waving and a few unsupported and comically unrealistic numbers, it does not appear that there has been any substantial progress toward addressing those challenges. Instead, proponents have simply kept changing the subject to trivial issues like ergonomics and video screens, before going back to the literal pipe dreams of a world with all of our transportation problems solved.

The key here is that the journalists covering the claims really want to believe them and that makes it all too easy to go along.















Wednesday, March 6, 2019

Consistency in news coverage

This is Joseph

In thinking about media criticism, I want to link to these tweets by Matt Yglesias:


They bring up the central issue with the Clinton email issue -- there has been no consistent follow-up with succeeding administrations. It is one thing to say national security is very important (and it is).  But if you set the standard that a minor breach of security protocols requires congressional hearings, you are stuck in the face of a major one with either:


  1. Admission that the previous claims were specious
  2. Rigorously pursuing the new (more serious) claims 
Otherwise we end up with an odd sort of double standard that undermines any sort of ability to actually plan for political outcomes. Very much like the "deficits matter only as long as the other party holds the presidency".  These odd double standards undermine coherent debate about national priorities and what voters want.  Insofar as the press has a privileged position as the 4th estate, it is to guide us in debate and not to cultivate random scandals just to drive interest. In this sense, social media models may be failing us even worse than I had previously worried.  


Tuesday, March 5, 2019

OK, one comment


I must be suffering from red flag fatigue. It wasn't until after I posted this that the significance of the following hit me.

From A Real Tube Carrying Dreams of 600-M.P.H. Transit by Eric Taub
    All three companies contend that because of energy cost advantages over other forms of transportation, a system will be able to break even in a decade after full-scale operations begin. 
No one knows how much it would cost to build and operate a hyperloop over a great enough distance to make the speed worth while. Using existing methods, a project requiring this level of precision on this scale would be obscenely expensive. In order to make a serious attempt, a company would have to come up with radically new approaches and technology.

If Virgin and the rest were each pursuing possible breakthroughs independently, we should be seeing big differences in their cost estimates, even if those estimates were wildly unrealistic. The fact that all three give the same time to break even point is curious.

I'm afraid the most likely explanation is that they haven't really done anything substantive on the construction side. They're still using the orifice-derived numbers from the original whitepaper, which are even more nonsensical since all of them have abandoned Musk's original air-caster proposal.

Monday, March 4, 2019

Presenting without comment something that should have been presented with comment in that NYT hyperloop article.

From A Real Tube Carrying Dreams of 600-M.P.H. Transit by Eric Taub [emphasis added]

All three companies contend that because of energy cost advantages over other forms of transportation, a system will be able to break even in a decade after full-scale operations begin. Not only will commuters be able to get from place to place faster, but doing so will allow people to comfortably live far from their work, giving access to educational, cultural and health services normally out of reach.


From the John A Volpe National Transportation Systems Center's  Hyperloop Commercial Feasibility Analysis

2.1.6 Energy consumption

“Hyperloop Alpha” emphasizes that the hyperloop technology will be completely solar powered. However, maglev and HSR are also electric and could in theory also be solar powered. Focusing on the amount of energy required, HT found that for most routes hyperloop would be 2 to 3 times more energy efficient than air on a passenger mile basis; however, maglev and HSR also use 1/3 the energy of air on a passenger mile basis. The emphasis on solar power tends to obscure the fact that no technology is entirely clean because there is energy consumed in manufacture and construction of the technology.